JP3964414B2 - Magnetostrictive torque sensor and electric steering device - Google Patents

Magnetostrictive torque sensor and electric steering device Download PDF

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JP3964414B2
JP3964414B2 JP2004245124A JP2004245124A JP3964414B2 JP 3964414 B2 JP3964414 B2 JP 3964414B2 JP 2004245124 A JP2004245124 A JP 2004245124A JP 2004245124 A JP2004245124 A JP 2004245124A JP 3964414 B2 JP3964414 B2 JP 3964414B2
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detection
magnetostrictive
output
detection coil
torque sensor
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JP2006064445A (en
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康夫 清水
義人 中村
俊一郎 末吉
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Honda Motor Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L3/00—Measuring torque, work, mechanical power, or mechanical efficiency, in general
    • G01L3/02—Rotary-transmission dynamometers
    • G01L3/04—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft
    • G01L3/10—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating
    • G01L3/101—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means
    • G01L3/102—Rotary-transmission dynamometers wherein the torque-transmitting element comprises a torsionally-flexible shaft involving electric or magnetic means for indicating involving magnetic or electromagnetic means involving magnetostrictive means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/22—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers
    • G01L5/221—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers to steering wheels, e.g. for power assisted steering

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Power Steering Mechanism (AREA)

Description

この発明は、磁歪に起因する磁気特性の変化に基づいてトルクを検出する磁歪式トルクセンサと、これを備えた電動ステアリング装置に関するものである。   The present invention relates to a magnetostrictive torque sensor that detects torque based on a change in magnetic characteristics caused by magnetostriction, and an electric steering device including the magnetostrictive torque sensor.

非接触式トルクセンサとして、磁歪に起因する磁気特性の変化に基づいてトルクを検出する磁歪式トルクセンサが知られている。磁歪式トルクセンサは、車両用ステアリング装置の操舵トルク検出用などに用いられている（特許文献１参照）。
この種の磁歪式トルクセンサには、図６に示すように、磁気異方性を異にする２つの磁歪膜９１，９２を回転シャフト９９に設けるとともに、各磁歪膜９１，９２に対向してそれぞれ検出コイル９３，９４を配置して構成されたものがある（特許文献２参照）。この磁歪式トルクセンサ９０の原理は、回転シャフト９９にトルクが加えられると磁歪膜９１，９２の透磁率が変化し、これに応じて検出コイル９３，９４のインダクタンスが変化するので、この変化に基づいてトルクを検出する。 As a non-contact type torque sensor, a magnetostrictive torque sensor that detects torque based on a change in magnetic characteristics caused by magnetostriction is known. The magnetostrictive torque sensor is used for detecting steering torque of a vehicle steering device (see Patent Document 1).
In this type of magnetostrictive torque sensor, as shown in FIG. 6, two magnetostrictive films 91 and 92 having different magnetic anisotropies are provided on the rotating shaft 99 and opposed to the magnetostrictive films 91 and 92, respectively. There is one configured by arranging detection coils 93 and 94, respectively (see Patent Document 2). The principle of the magnetostrictive torque sensor 90 is that when the torque is applied to the rotary shaft 99, the magnetic permeability of the magnetostrictive films 91, 92 changes, and the inductance of the detection coils 93, 94 changes accordingly. Torque is detected based on this.

ところで、この種の磁歪式トルクセンサを用いる場合、トルクを検出する際に該トルクセンサの故障検出を行う必要がある。
前述した２つの磁歪膜９１，９２を備えた磁歪式トルクセンサ９０の場合においては、トルクを検出するときには一方の検出コイル９３の検出出力（以下、第１検出出力ＶＴ１と称す）と他方の検出コイル９４の検出出力（以下、第２検出出力ＶＴ２と称す）の差に基づいてトルク検出出力ＶＴ３を算出し、故障を検出するときには第１検出出力ＶＴ１と第２検出出力ＶＴ２の和に基づいて故障検出出力ＶＴＦを算出し閾値との比較から故障を検出している。 By the way, when this type of magnetostrictive torque sensor is used, it is necessary to detect a failure of the torque sensor when detecting the torque.
In the case of the magnetostrictive torque sensor 90 having the two magnetostrictive films 91 and 92 described above, when detecting torque, the detection output of one detection coil 93 (hereinafter referred to as the first detection output VT1) and the other detection are detected. Torque detection output VT3 is calculated based on the difference in detection output of coil 94 (hereinafter referred to as second detection output VT2), and based on the sum of first detection output VT1 and second detection output VT2 when a failure is detected. A failure detection output VTF is calculated and a failure is detected by comparison with a threshold value.

図７は（１）式に基づいてトルク検出出力ＶＴ３を算出した場合の出力特性図であり、図８は（２）式に基づいて故障検出出力ＶＴＦを算出した場合の出力特性図である。なお、（１）式、（２）式において、ｋ、Ｖ０，Ｃは定数である。
ＶＴ３＝ｋ・（ＶＴ１−ＶＴ２）＋Ｖ０ ・・・ （１）式
ＶＴＦ＝｜ＶＴ１＋ＶＴ２｜−Ｃ ・・・ （２）式
特開２００２−３１６６５８号公報 特開昭５９−１６４９３２号公報 FIG. 7 is an output characteristic diagram when the torque detection output VT3 is calculated based on the equation (1), and FIG. 8 is an output characteristic diagram when the failure detection output VTF is calculated based on the equation (2). In equations (1) and (2), k, V0, and C are constants.
VT3 = k · (VT1-VT2) + V0 (1) Formula VTF = | VT1 + VT2 | −C (2)
JP 2002-316658 A JP 59-164932 A

ところで、一般に、磁歪膜は、温度が高いほど透磁率が増加する温度特性を有している。そのため、前記磁歪式トルクセンサ９０においては、温度変化により磁歪膜９１，９２の透磁率が変化すると、各検出コイル９３，９４の第１検出出力ＶＴ１、第２検出出力ＶＴ２も変化することとなる。このときに、温度変化により第１検出出力ＶＴ１と第２検出出力ＶＴ２が図７において点線で示すように変化した場合には、トルク検出出力ＶＴ３は第１検出出力ＶＴ１と第２検出出力ＶＴ２の差動出力であることから、温度変化による影響を殆ど受けない。したがって、この場合には、温度変化があってもトルク検出出力ＶＴ３は正しい値となる。   By the way, in general, the magnetostrictive film has a temperature characteristic in which the magnetic permeability increases as the temperature increases. Therefore, in the magnetostrictive torque sensor 90, when the magnetic permeability of the magnetostrictive films 91 and 92 changes due to a temperature change, the first detection output VT1 and the second detection output VT2 of the detection coils 93 and 94 also change. . At this time, if the first detection output VT1 and the second detection output VT2 change as indicated by the dotted line in FIG. 7 due to the temperature change, the torque detection output VT3 is the first detection output VT1 and the second detection output VT2. Since it is a differential output, it is hardly affected by temperature changes. Therefore, in this case, the torque detection output VT3 has a correct value even if there is a temperature change.

しかしながら、故障検出出力ＶＴＦは第１検出出力ＶＴ１と第２検出出力ＶＴ２の和動出力であることから、温度変化により第１検出出力ＶＴ１と第２検出出力ＶＴ２が図８において点線で示すように変化すると、故障検出出力ＶＴＦも温度変化による影響を受けることとなり、場合によっては図８において破線で示されるように故障検出出力ＶＴＦが故障検出Ａから外れてしまい、トルクセンサが正常であるにも関わらず故障とみなされてしまう。   However, since the failure detection output VTF is a summed output of the first detection output VT1 and the second detection output VT2, the first detection output VT1 and the second detection output VT2 are indicated by dotted lines in FIG. If the change occurs, the failure detection output VTF is also affected by the temperature change. In some cases, the failure detection output VTF deviates from the failure detection A as shown by the broken line in FIG. 8, and the torque sensor is normal. Regardless, it is considered a failure.

また、前述した磁歪式トルクセンサを車両に搭載して用いた場合であって、例えば、路面に磁石が設置してあったり、あるいは、スタータモータなどのアクチュエータを大電流で起動したときなどに、車室内に磁場変化が発生すると、第１検出出力ＶＴ１および第２検出出力ＶＴ２が変化する場合がある。このときに、磁場変化により第１検出出力ＶＴ１と第２検出出力ＶＴ２が図９において点線で示すように変化した場合には、トルク検出出力ＶＴ３は第１検出出力ＶＴ１と第２検出出力ＶＴ２の差動出力であることから、磁場変化による影響を殆ど受けない。したがって、この場合には、磁場変化があってもトルク検出出力ＶＴ３は正しい値となる。   In addition, when the above-described magnetostrictive torque sensor is mounted on a vehicle and used, for example, when a magnet is installed on the road surface, or when an actuator such as a starter motor is activated with a large current, When a magnetic field change occurs in the passenger compartment, the first detection output VT1 and the second detection output VT2 may change. At this time, if the first detection output VT1 and the second detection output VT2 change as indicated by the dotted line in FIG. 9 due to the magnetic field change, the torque detection output VT3 is the first detection output VT1 and the second detection output VT2. Since it is a differential output, it is hardly affected by changes in the magnetic field. Therefore, in this case, the torque detection output VT3 has a correct value even if the magnetic field changes.

しかしながら、故障検出出力ＶＴＦは第１検出出力ＶＴ１と第２検出出力ＶＴ２の和動出力であることから、磁場変化により第１検出出力ＶＴ１と第２検出出力ＶＴ２が図１１において点線で示すように変化すると、故障検出出力ＶＴＦも磁場変化による影響を受けることとなり、場合によっては図１０、図１１に示されるように故障検出出力ＶＴＦが故障検出閾値Ａから外れてしまい、トルクセンサが正常であるにも関わらず故障とみなされてしまう虞がある。
そこで、この発明は、温度変化や磁場変化による影響を受けずに故障検出が可能な磁歪式トルクセンサと、これを備えた信頼性の高い電動ステアリング装置を提供するものである。 However, since the failure detection output VTF is a sum output of the first detection output VT1 and the second detection output VT2, the first detection output VT1 and the second detection output VT2 are indicated by dotted lines in FIG. When the change occurs, the failure detection output VTF is also affected by the change in the magnetic field. In some cases, the failure detection output VTF deviates from the failure detection threshold A as shown in FIGS. 10 and 11, and the torque sensor is normal. Nevertheless, there is a risk of being regarded as a failure.
Accordingly, the present invention provides a magnetostrictive torque sensor capable of detecting a failure without being affected by a temperature change or a magnetic field change, and a highly reliable electric steering apparatus including the magnetostrictive torque sensor.

上記課題を解決するために、請求項１に係る発明は、シャフト（例えば、後述する実施例におけるステアリングシャフト１）に設けられた磁気異方性を互いに異にする第１磁歪膜（例えば、後述する実施例における第１磁歪膜３１）と第２磁歪膜（例えば、後述する実施例における第２磁歪膜３２）の磁気特性の変化に基づいて前記シャフトに入力されるトルクを検出する磁歪式トルクセンサであって、前記第１磁歪膜に対向配置された第１検出コイル（例えば、後述する実施例における第１検出コイル３３）および第２検出コイル（例えば、後述する実施例における第２検出コイル３４）と、前記第２磁歪膜に対向配置された第３検出コイル（例えば、後述する実施例における第３検出コイル３５）および第４検出コイル（例えば、後述する実施例における第４検出コイル３６）と、を備え、前記第１検出コイルの出力と前記第２検出コイルの出力との差に対応する第１信号（例えば、後述する実施例における差動電圧ＶＴＦ１）と、前記第３検出コイルの出力と前記第４検出コイルの出力との差に対応する第２信号（例えば、後述する実施例における差動電圧ＶＴＦ２）と、を求め、前記第１信号と前記第２信号の和または差に対応する故障検出信号（例えば、後述する実施例における故障検出電圧ＶＴＦ３）に基づいて自身の故障を検出することを特徴とする磁歪式トルクセンサ（例えば、後述する実施例における磁歪式トルクセンサ３０）である。
また、請求項２に係る発明は、シャフト（例えば、後述する実施例におけるステアリングシャフト１）に設けられた磁気異方性を互いに異にする第１磁歪膜（例えば、後述する実施例における第１磁歪膜３１）と第２磁歪膜（例えば、後述する実施例における第２磁歪膜３２）の磁気特性の変化に基づいて前記シャフトに入力されるトルクを検出する磁歪式トルクセンサであって、前記第１磁歪膜に対向配置された第１検出コイル（例えば、後述する実施例における第１検出コイル３３）および第２検出コイル（例えば、後述する実施例における第２検出コイル３４）と、前記第２磁歪膜に対向配置された第３検出コイル（例えば、後述する実施例における第３検出コイル３５）および第４検出コイル（例えば、後述する実施例における第４検出コイル３６）と、を備え、前記第１検出コイルの出力と前記第３検出コイルの出力との差に対応する第３信号（例えば、後述する実施例における差動電圧ＶＴ３１）と、前記第２検出コイルの出力と前記第４検出コイルの出力との差に対応する第４信号（例えば、後述する実施例における差動電圧ＶＴ３２）と、を求め、前記第３信号と前記第４信号の差に対応する故障検出信号（例えば、後述する実施例における故障検出電圧ＶＴＦ４）に基づいて自身の故障を検出することを特徴とする磁歪式トルクセンサ（例えば、後述する実施例における磁歪式トルクセンサ３０）である。
このように構成すると、温度変化や磁場変化に起因する磁気特性の変化を相殺することができ、その結果、温度変化や磁場変化の影響を受けずに高精度で故障検出を行うことができる。 In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a first magnetostrictive film (for example, described later) having different magnetic anisotropies provided on a shaft (for example, a steering shaft 1 in an embodiment described later). Magnetostrictive torque for detecting torque input to the shaft based on a change in magnetic characteristics of the first magnetostrictive film 31) and the second magnetostrictive film (for example, the second magnetostrictive film 32 in the embodiments described later). A first detection coil (for example, a first detection coil 33 in an embodiment to be described later) and a second detection coil (for example, a second detection coil in an embodiment to be described later) that are sensors and are disposed to face the first magnetostrictive film. 34), a third detection coil (for example, a third detection coil 35 in an embodiment described later) and a fourth detection coil (for example, described later) disposed opposite to the second magnetostrictive film. A fourth detection coil 36) in Example, wherein the first first signal corresponding to the difference between the output of the detection coil and the output of the previous SL second detection coil (e.g., the differential voltage in the embodiment described later and VTF1), a second signal corresponding to the difference between the output of the third detection output before Symbol fourth detection coil of the coil (e.g., seeking a differential voltage VTF2) in examples described later, the first A magnetostrictive torque sensor (e.g., detecting a failure of itself based on a failure detection signal (e.g., failure detection voltage VTF3 in an embodiment described later) corresponding to the sum or difference of the signal and the second signal) This is a magnetostrictive torque sensor 30) in an embodiment described later.
According to a second aspect of the present invention, there is provided a first magnetostrictive film (for example, a first magnetostrictive film according to an embodiment described later) having different magnetic anisotropies provided to a shaft (for example, a steering shaft 1 according to an embodiment described later). A magnetostrictive torque sensor for detecting torque input to the shaft based on a change in magnetic characteristics of a magnetostrictive film 31) and a second magnetostrictive film (for example, a second magnetostrictive film 32 in an embodiment described later), A first detection coil (for example, a first detection coil 33 in an embodiment to be described later) and a second detection coil (for example, a second detection coil 34 in an embodiment to be described later) disposed opposite to the first magnetostrictive film; The third detection coil (for example, the third detection coil 35 in the embodiment described later) and the fourth detection coil (for example, the fourth in the embodiment described later) disposed opposite to the two magnetostrictive films. And a third signal corresponding to a difference between the output of the first detection coil and the output of the third detection coil (for example, a differential voltage VT31 in an embodiment described later), A fourth signal corresponding to the difference between the output of the second detection coil and the output of the fourth detection coil (for example, a differential voltage VT32 in an embodiment to be described later), and the third signal and the fourth signal A magnetostrictive torque sensor (for example, a magnetostrictive torque sensor in an embodiment described later), which detects its own failure based on a failure detection signal corresponding to the difference (for example, a failure detection voltage VTF4 in the embodiment described later). 30).
With this configuration, it is possible to cancel changes in magnetic characteristics caused by temperature changes and magnetic field changes, and as a result, failure detection can be performed with high accuracy without being affected by temperature changes and magnetic field changes.

請求項３に係る発明は、操舵トルクを磁歪式トルクセンサによって検出し、検出した操舵トルクに応じて電動機（例えば、後述する実施例における電動機１１）を駆動して車両を転舵させる電動ステアリング装置（例えば、後述する実施例における電動パワーステアリング装置１００）において、前記磁歪式トルクセンサは請求項１または請求項２に記載の磁歪式トルクセンサ（例えば、後述する実施例における磁歪式トルクセンサ３０）であることを特徴とする。
このように構成することにより、電動ステアリング装置の操舵トルクを検出するための磁歪式トルクセンサが、正常であるにもかかわらず温度変化や磁場変化に起因して故障であると誤検出するのを防止することができる。 According to a third aspect of the present invention, there is provided an electric steering device for detecting a steering torque by a magnetostrictive torque sensor and driving an electric motor (for example, an electric motor 11 in an embodiment to be described later) in accordance with the detected steering torque to steer the vehicle. (For example, in the electric power steering apparatus 100 in the embodiment described later), the magnetostrictive torque sensor is the magnetostrictive torque sensor according to claim 1 or 2 (for example, the magnetostrictive torque sensor 30 in the embodiment described later). It is characterized by being.
With this configuration, the magnetostrictive torque sensor for detecting the steering torque of the electric steering device erroneously detects a failure due to a temperature change or a magnetic field change even though it is normal. Can be prevented.

請求項１あるいは請求項２に係る発明によれば、温度変化や磁場変化の影響を受けずに高精度で磁歪式トルクセンサの故障検出を行うことができ、その結果、磁歪式トルクセンサの信頼性が向上する。
請求項３に係る発明によれば、電動ステアリング装置の操舵トルクを検出するための磁歪式トルクセンサが、正常であるにもかかわらず温度変化や磁場変化に起因して故障であると誤検出するのを防止することができ、電動ステアリング装置の信頼性が向上する。 According to the first or second aspect of the present invention, it is possible to detect the failure of the magnetostrictive torque sensor with high accuracy without being affected by the temperature change or the magnetic field change. Improves.
According to the third aspect of the present invention, the magnetostrictive torque sensor for detecting the steering torque of the electric steering device erroneously detects a failure due to a temperature change or a magnetic field change despite being normal. Can be prevented, and the reliability of the electric steering apparatus is improved.

以下、この発明に係る磁歪式トルクセンサとこれを備えた電動ステアリング装置の実施例を図１から図５の図面を参照して説明する。
図１に示すように、車両用電動パワーステアリング装置（電動ステアリング装置）１００はハンドル（操舵手段）２に連結されたステアリングシャフト１を備えている。ステアリングシャフト１は、ハンドル２に一体結合されたメインステアリングシャフト３と、ラック＆ピニオン機構のピニオン７が設けられたピニオン軸５とが、ユニバーサルジョイント４によって連結されて構成されている。
ピニオン軸５はその下部、中間部、上部を軸受６ａ，６ｂ，６ｃによって支持されており、ピニオン７はピニオン軸５の下端部に設けられている。ピニオン７は、車幅方向に往復動し得るラック軸８のラック歯８ａに噛合し、ラック軸８の両端には、タイロッド９，９を介して転舵輪としての左右の前輪１０，１０が連結されている。この構成により、ハンドル２の操舵時に通常のラック＆ピニオン式の転舵操作が可能であり、前輪１０，１０を転舵させて車両の向きを変えることができる。ここで、ラック軸８、ラック８ａ、タイロッド９，９は転舵機構を構成する。 DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a magnetostrictive torque sensor and an electric steering apparatus having the magnetostrictive torque sensor according to the present invention will be described below with reference to the drawings of FIGS.
As shown in FIG. 1, a vehicle electric power steering device (electric steering device) 100 includes a steering shaft 1 connected to a handle (steering means) 2. The steering shaft 1 is constituted by connecting a main steering shaft 3 integrally coupled to a handle 2 and a pinion shaft 5 provided with a pinion 7 of a rack and pinion mechanism by a universal joint 4.
The lower part, the middle part, and the upper part of the pinion shaft 5 are supported by bearings 6 a, 6 b and 6 c, and the pinion 7 is provided at the lower end part of the pinion shaft 5. The pinion 7 meshes with the rack teeth 8a of the rack shaft 8 that can reciprocate in the vehicle width direction. Has been. With this configuration, a normal rack and pinion type steering operation can be performed when the steering wheel 2 is steered, and the front wheels 10 and 10 can be steered to change the direction of the vehicle. Here, the rack shaft 8, the rack 8a, and the tie rods 9 and 9 constitute a steering mechanism.

また、電動パワーステアリング装置１００は、ハンドル２による操舵力を軽減するための補助操舵力を供給する電動機１１を備えており、この電動機１１の出力軸に設けられたウォームギヤ１２が、ピニオン軸５において中間部の軸受６ｂの下側に設けられたウォームホイールギヤ１３に噛合している。   In addition, the electric power steering apparatus 100 includes an electric motor 11 that supplies an auxiliary steering force for reducing the steering force by the handle 2. It meshes with a worm wheel gear 13 provided below the intermediate bearing 6b.

また、ピニオン軸５において中間部の軸受６ｂと上部の軸受６ｃとの間には、磁歪に起因する磁気特性の変化に基づいてトルクを検出する磁歪式トルクセンサ３０が配置されている。
磁歪式トルクセンサ３０は、ピニオン軸５の外周面に周方向全周に亘って環状に設けられた第１磁歪膜３１および第２磁歪膜３２と、第１磁歪膜３１に対向配置された第１検出コイル３３および第２検出コイル３４と、第２磁歪膜３２に対向配置された第３検出コイル３５および第４検出コイル３６と、第１、第２、第３、第４検出コイル３３，３４，３５，３６にそれぞれ接続された検出回路３７，３８，３９，４０を主要構成としている。
第１、第２磁歪膜３１，３２は、歪みに対して透磁率の変化が大きい素材からなる金属膜であり、例えば、ピニオン軸５の外周にメッキ法で形成したＮｉ−Ｆｅ系の合金膜からなる。 In the pinion shaft 5, a magnetostrictive torque sensor 30 that detects torque based on a change in magnetic characteristics caused by magnetostriction is disposed between the intermediate bearing 6b and the upper bearing 6c.
The magnetostrictive torque sensor 30 includes a first magnetostrictive film 31 and a second magnetostrictive film 32 that are annularly provided on the outer peripheral surface of the pinion shaft 5 over the entire circumferential direction, and a first magnetostrictive film 31 that is disposed opposite to the first magnetostrictive film 31. 1 detection coil 33 and 2nd detection coil 34, 3rd detection coil 35 and 4th detection coil 36 which are arranged opposite to the 2nd magnetostriction film 32, 1st, 2nd, 3rd, 4th detection coil 33, Detection circuits 37, 38, 39, and 40 connected to 34, 35, and 36, respectively, are the main components.
The first and second magnetostrictive films 31 and 32 are metal films made of a material having a large change in magnetic permeability with respect to strain. For example, a Ni—Fe alloy film formed by plating on the outer periphery of the pinion shaft 5. Consists of.

第１磁歪膜３１は、ピニオン軸５の軸線に対して約４５度傾斜した方向に磁気異方性を備えるように構成されており、第２磁歪膜３２は、第１磁歪膜３１の磁気異方性の方向に対して約９０度傾斜した方向に磁気異方性を備えるように構成されている。すなわち、２つの磁歪膜３１，３２の磁気異方性は互いに約９０度位相を異にしている。
第１検出コイル３３および第２検出コイル３４は、第１磁歪膜３１の周囲にこれと所定の隙間を有した状態で同軸状に配置されており、ピニオン軸５の軸線方向に互いにずらして配置されている。
第３検出コイル３５および第４検出コイル３６は、第２磁歪膜３２の周囲にこれと所定の隙間を有した状態で同軸状に配置されており、ピニオン軸５の軸線方向に互いにずらして配置されている。 The first magnetostrictive film 31 is configured to have magnetic anisotropy in a direction inclined by about 45 degrees with respect to the axis of the pinion shaft 5, and the second magnetostrictive film 32 is magnetically different from the first magnetostrictive film 31. The magnetic anisotropy is provided in a direction inclined by about 90 degrees with respect to the direction of the isotropic property. That is, the magnetic anisotropy of the two magnetostrictive films 31 and 32 are approximately 90 degrees out of phase with each other.
The first detection coil 33 and the second detection coil 34 are coaxially arranged around the first magnetostrictive film 31 with a predetermined gap therebetween, and are shifted from each other in the axial direction of the pinion shaft 5. Has been.
The third detection coil 35 and the fourth detection coil 36 are disposed coaxially around the second magnetostrictive film 32 with a predetermined gap therebetween, and are shifted from each other in the axial direction of the pinion shaft 5. Has been.

第１、第２磁歪膜３１，３２の磁気異方性を前述のように設定したことにより、ピニオン軸５にトルクが作用した状態では、磁歪膜３１，３２の一方に圧縮力が作用し、他方に引っ張り力が作用するようになり、その結果、一方の磁歪膜の透磁率が増加し、他方の磁歪膜の透磁率が減少する。そして、これに応じて一方の磁歪膜の周囲に配置された２つの検出コイルのインダクタンスが増加し、他方の磁歪膜の周囲に配置された２つの検出コイルのインダクタンスが減少する。
第１、第２、第３、第４検出コイル３３，３４，３５，３６は、それぞれ変換回路を備えた検出回路３７，３８，３９，４０に接続されており、これら検出回路３７〜４０において各検出コイル３３〜３６のインダクタンス変化は電圧変化に変換されて電子制御装置（ＥＣＵ）５０に出力される。 By setting the magnetic anisotropy of the first and second magnetostrictive films 31 and 32 as described above, a compressive force acts on one of the magnetostrictive films 31 and 32 in a state where torque acts on the pinion shaft 5, A tensile force acts on the other, and as a result, the magnetic permeability of one magnetostrictive film increases and the magnetic permeability of the other magnetostrictive film decreases. Accordingly, the inductances of the two detection coils arranged around one magnetostrictive film are increased, and the inductances of the two detection coils arranged around the other magnetostrictive film are reduced.
The first, second, third, and fourth detection coils 33, 34, 35, and 36 are connected to detection circuits 37, 38, 39, and 40 each having a conversion circuit, and in these detection circuits 37 to 40, respectively. An inductance change of each of the detection coils 33 to 36 is converted into a voltage change and output to an electronic control unit (ECU) 50.

ＥＣＵ５０は、検出回路３７〜４０からの出力電圧に基づいて、ピニオン軸５に作用する操舵トルクの検出と、磁歪式トルクセンサ３０の故障検出を実行する。以下、この実施例におけるトルク検出電圧ＶＴ３と故障検出電圧ＶＴＦの算出方法を説明する。
いま、検出回路３７の出力電圧をＶＴ１１、検出回路３８の出力電圧をＶＴ１２、検出回路３９の出力電圧をＶＴ２１、検出回路４０の出力電圧をＶＴ２２とする。 The ECU 50 detects the steering torque acting on the pinion shaft 5 and detects the failure of the magnetostrictive torque sensor 30 based on the output voltages from the detection circuits 37 to 40. Hereinafter, a method for calculating the torque detection voltage VT3 and the failure detection voltage VTF in this embodiment will be described.
Now, the output voltage of the detection circuit 37 is VT11, the output voltage of the detection circuit 38 is VT12, the output voltage of the detection circuit 39 is VT21, and the output voltage of the detection circuit 40 is VT22.

トルク検出電圧ＶＴ３を算出する場合には、まず、次の（３）式および（４）式により差動電圧ＶＴ３１，ＶＴ３２を、または（３）式および（５）式により差動電圧ＶＴ３１，ＶＴ３３を算出する。ここで、ｋ１１、ｋ１２、ｋ２１、ｋ２２は比例定数、Ｖ０は一定数、Ｔは操舵トルクである。
ＶＴ３１＝ＶＴ１１−ＶＴ２１＋Ｖ０＝ｋ１１・Ｔ−（−ｋ２１・Ｔ）＝（ｋ１１＋ｋ２１）Ｔ ・・・ （３）式
ＶＴ３２＝ＶＴ１２−ＶＴ２２＋Ｖ０＝ｋ１２・Ｔ−（−ｋ２２・Ｔ）＝（ｋ１２＋ｋ２２）Ｔ ・・・ （４）式
ＶＴ３３＝ＶＴ２２−ＶＴ１２＋Ｖ０＝−ｋ２２・Ｔ−（ｋ１２・Ｔ）＝−（ｋ１２＋ｋ２２）Ｔ ・・・ （５）式
つまり、差動電圧ＶＴ３１は、第１磁歪膜３１に対向配置された第１検出コイル３３と第２磁歪膜３２に対向配置された第３検出コイル３５の差動電圧（差動出力）であり、差動電圧ＶＴ３２と差動電圧ＶＴ３３は、第１磁歪膜３１に対向配置された第２検出コイル３４と第２磁歪膜３２に対向配置された第４検出コイル３６の差動電圧（差動出力）である。 When calculating the torque detection voltage VT3, first, the differential voltages VT31 and VT32 are calculated by the following equations (3) and (4), or the differential voltages VT31 and VT33 are calculated by the equations (3) and (5). Is calculated. Here, k11, k12, k21, and k22 are proportional constants, V0 is a fixed number, and T is steering torque.
VT31 = VT11−VT21 + V0 = k11 · T − (− k21 · T) = (k11 + k21) T (3) Expression VT32 = VT12−VT22 + V0 = k12 · T − (− k22 · T) = (k12 + k22) T (4) Equation VT33 = VT22−VT12 + V0 = −k22 · T− (k12 · T) = − (k12 + k22) T (5) That is, the differential voltage VT31 is opposed to the first magnetostrictive film 31. This is a differential voltage (differential output) between the first detection coil 33 and the third detection coil 35 disposed opposite to the second magnetostrictive film 32. The differential voltage VT32 and the differential voltage VT33 are the first magnetostriction. This is a differential voltage (differential output) between the second detection coil 34 disposed opposite to the film 31 and the fourth detection coil 36 disposed opposite to the second magnetostrictive film 32.

そして、トルク検出電圧ＶＴ３は、ＶＴ３１かＶＴ３２のどちらかを使用するので、（３）式においてｋ１１とｋ２１はほぼ等しいので、ＶＴ３１は、操舵トルクＴに対してＶＴ１１やＶＴ２１より約２倍のゲインとなる。また同様に（４）式においてもｋ１２とｋ２２はほぼ等しいのでＶＴ３２は、操舵トルクに対してＶＴ１２やＶＴ２２より約２倍のゲインとなるので、感度は２倍となる。
また別の方法として、次の（６）式により、差動電圧ＶＴ３１とＶＴ３３の差からトルク検出電圧ＶＴ３を算出する。
ＶＴ３＝ＶＴ３１−ＶＴ３３＋Ｖ０＝（ｋ１１＋ｋ１２＋ｋ２１＋ｋ２２）Ｔ ・・・ （６）式
（６）式より、ＶＴ３は、ＶＴ１１〜ＶＴ２２より感度を約４倍に向上させることができる効果を有する。 Then, the torque detection voltage VT3, since use either VT31 or VT32, (3) since k11 and k 21 is approximately equal in type, VT31 is about 2 times greater than VT11 and VT 21 with respect to the steering torque T Gain. Similarly, in equation (4), k12 and k22 are substantially equal, so VT32 has a gain approximately twice that of VT12 or VT22 with respect to the steering torque, so the sensitivity is doubled.
As another method, the torque detection voltage VT3 is calculated from the difference between the differential voltages VT31 and VT33 by the following equation (6).
VT3 = VT31-VT33 + V0 = (k11 + k12 + k21 + k22) T ··· (6) from equation (6), VT 3 has the advantage of being able to improve sensitivity than VT11~VT22 about four times.

次に、故障検出電圧ＶＴＦを算出する場合には、まず、次の（７）式および（８）式により差動電圧ＶＴＦ１，ＶＴＦ２を算出する。
ＶＴＦ１＝ＶＴ１１−ＶＴ１２ ・・・ （７）式
ＶＴＦ２＝ＶＴ２１−ＶＴ２２ ・・・ （８）式
つまり、差動電圧（第１差動信号）ＶＴＦ１は、第１磁歪膜３１に対向配置された第１検出コイル３３と第２検出コイル３４の差動電圧（差動出力）であり、差動電圧（第２差動信号）ＶＴＦ２は、第２磁歪膜３２に対向配置された第３検出コイル３５と第４検出コイル３６の差動電圧（差動出力）である。
そして、ＶＴＦ１とＶＴＦ２のうち少なくとも何れか一方が故障検出閾値Ａから外れたときには故障と判定する。
また、別の方法として、次の（９）式、または（１０）式により、差動電圧ＶＴＦ１，ＶＴＦ２の和、または差から故障検出電圧ＶＴＦ３を算出する。
ＶＴＦ３＝ＶＴＦ１＋ＶＴＦ２ ・・・ （９）式
ＶＴＦ３＝ＶＴＦ１−ＶＴＦ２ ・・・ （１０）式
そして、ＶＴＦ３が故障検出閾値Ａから外れたときには故障と判定する。 Next, when calculating the failure detection voltage VTF, first, the differential voltages VTF1 and VTF2 are calculated by the following equations (7) and (8).
VTF1 = VT11−VT12 (7) Formula VTF2 = VT21−VT22 (8) That is, the differential voltage (first differential signal) VTF1 is the first magnetostrictive film 31 disposed opposite to the first magnetostrictive film 31. The differential voltage (differential output) between the first detection coil 33 and the second detection coil 34, and the differential voltage (second differential signal) VTF 2 is disposed in the second magnetostrictive film 32 so as to face the third detection coil 35. And the differential voltage (differential output) of the fourth detection coil 36.
When at least one of VTF1 and VTF2 deviates from the failure detection threshold A, it is determined that there is a failure.
As another method, the failure detection voltage VTF3 is calculated from the sum or difference of the differential voltages VTF1 and VTF2 by the following equation (9) or equation (10).
VTF3 = VTF1 + VTF2 (9) Expression VTF3 = VTF1-VTF2 (10) And, when VTF3 deviates from the failure detection threshold A, it is determined that there is a failure.

ＥＣＵ５０は、検出されたトルク検出電圧ＶＴ３１、またはＶＴ３２、またはＶＴ３３に応じて電動機１１の目標電流を設定し、該目標電流によって電動機１１を駆動して補助操舵力を発生させ、車両を転舵させる。また、ＥＣＵ５０は、故障検出出力ＶＴＦ１、またはＶＴＦ２、またはＶＴＦ３が所定の閾値Ａを超えたときに磁歪式トルクセンサ３０が故障であると判定する。   The ECU 50 sets a target current of the electric motor 11 according to the detected torque detection voltage VT31, VT32, or VT33, drives the electric motor 11 with the target current to generate an auxiliary steering force, and steers the vehicle. . Further, the ECU 50 determines that the magnetostrictive torque sensor 30 is in failure when the failure detection output VTF1, VTF2, or VTF3 exceeds a predetermined threshold A.

ところで、第１磁歪膜３１と第２磁歪膜３２は、温度が高いほど透磁率が増加する温度特性を有しているため、ピニオン軸５に同じトルクが加えられているときであっても、温度変化によって、各検出回路３７，３８，３９，４０の出力電圧ＶＴ１，ＶＴ２，ＶＴ３，ＶＴ４が変化する。
図２は、第１磁歪膜３１の第１、第２検出コイル３３，３４に対応する検出回路３７，３８の出力電圧ＶＴ１１，ＶＴ１２の出力特性図であり、温度２０゜Ｃのときを実線で、温度８０゜Ｃのときを破線で示している。
図３は、第２磁歪膜３２の第３、第４検出コイル３５，３６に対応する検出回路３９，４０の出力電圧ＶＴ２１，ＶＴ２２の出力特性図であり、温度２０゜Ｃのときを実線で、温度８０゜Ｃのときを破線で示している。 By the way, since the first magnetostrictive film 31 and the second magnetostrictive film 32 have temperature characteristics in which the magnetic permeability increases as the temperature increases, even when the same torque is applied to the pinion shaft 5, The output voltages VT1, VT2, VT3, and VT4 of the detection circuits 37, 38, 39, and 40 change due to temperature changes.
FIG. 2 is an output characteristic diagram of the output voltages VT11 and VT12 of the detection circuits 37 and 38 corresponding to the first and second detection coils 33 and 34 of the first magnetostrictive film 31, and a solid line when the temperature is 20 ° C. When the temperature is 80 ° C., it is indicated by a broken line.
FIG. 3 is an output characteristic diagram of the output voltages VT21 and VT22 of the detection circuits 39 and 40 corresponding to the third and fourth detection coils 35 and 36 of the second magnetostrictive film 32, and a solid line at a temperature of 20 ° C. When the temperature is 80 ° C., it is indicated by a broken line.

図４は、トルク検出電圧ＶＴ３１、ＶＴ３２、ＶＴ３の出力特性図であり、出力電圧ＶＴ１１，ＶＴ１２と出力電圧ＶＴ２１，ＶＴ２２も重ねて示している。この出力特性図からわかるように、出力電圧ＶＴ１１，ＶＴ１２，ＶＴ２１，ＶＴ２２は温度によって変化するが、出力電圧ＶＴ１１，ＶＴ２１の差動電圧ＶＴ３１、および、出力電圧ＶＴ１２，ＶＴ２２の差動電圧ＶＴ３２は温度にかかわらず同じ値になる。したがって、差動電圧ＶＴ３１もしくは差動電圧ＶＴ３２であるトルク検出電圧ＶＴ３も、あるいは差動電圧ＶＴ３１，ＶＴ３３との差動電圧であるトルク検出電圧ＶＴ３も、温度にかかわらず同じ値になる。その結果、この電動パワーステアリング装置１００においては、温度変化による磁気特性の変化の影響を受けることなく、ピニオン軸５に作用するトルクを高精度で検出することができる。 FIG. 4 is an output characteristic diagram of the torque detection voltages VT31, VT32, and VT3. The output voltages VT11 and VT12 and the output voltages VT21 and VT22 are also shown in an overlapping manner. As can be seen from this output characteristic diagram, the output voltages VT11, VT12, VT21, and VT22 vary with temperature, but the differential voltage VT31 of the output voltages VT11 and VT21 and the differential voltage VT32 of the output voltages VT12 and VT22 are temperature. It becomes the same value regardless of. Therefore, the torque detection voltage VT3 which is the differential voltage VT31 or the differential voltage VT32, or the torque detection voltage VT3 which is a differential voltage with respect to the differential voltages VT31 and VT33 has the same value regardless of the temperature. As a result, in the electric power steering apparatus 100, the torque acting on the pinion shaft 5 can be detected with high accuracy without being affected by the change in magnetic characteristics due to the temperature change.

また、図２から明らかなように、出力電圧ＶＴ１１，ＶＴ１２は温度によって変化するが、これら２つの出力電圧ＶＴ１１，ＶＴ１２の差動電圧ＶＴＦ１は温度にかかわらず同じ値にある。さらに、図３から明らかなように、出力電圧ＶＴ２１，ＶＴ２２は温度によって変化するが、これら２つの出力電圧ＶＴ２１，ＶＴ２２の差動電圧ＶＴＦ２は温度にかかわらず同じ値になる。したがって、図５に示すように、これら差動電圧である故障検出電圧ＶＴＦ１，ＶＴＦ２も温度にかかわらず同じ値になる。また、差動電圧ＶＴＦ１とＶＴＦ２の和または差から算出した故障検出電圧ＶＴＦ３も同様に温度にかかわらず同じ値になる。その結果、この電動パワーステアリング装置１００においては、温度変化による磁気特性の変化の影響を受けることなく、磁歪式トルクセンサ３０の故障検出を高精度で行うことができ、磁歪式トルクセンサ３０が正常であるにも関わらず温度変化に起因して故障と判断されるのを防止することができる。   As is clear from FIG. 2, the output voltages VT11 and VT12 vary depending on the temperature, but the differential voltage VTF1 of these two output voltages VT11 and VT12 has the same value regardless of the temperature. Further, as apparent from FIG. 3, the output voltages VT21 and VT22 vary with temperature, but the differential voltage VTF2 of these two output voltages VT21 and VT22 has the same value regardless of the temperature. Therefore, as shown in FIG. 5, the failure detection voltages VTF1 and VTF2 which are these differential voltages have the same value regardless of the temperature. Similarly, the failure detection voltage VTF3 calculated from the sum or difference of the differential voltages VTF1 and VTF2 also has the same value regardless of the temperature. As a result, in this electric power steering apparatus 100, failure detection of the magnetostrictive torque sensor 30 can be performed with high accuracy without being affected by changes in magnetic characteristics due to temperature changes, and the magnetostrictive torque sensor 30 is normal. However, it is possible to prevent a failure from being determined due to a temperature change.

なお、磁場変化による影響を受けて検出回路３７〜４０の検出電圧ＶＴ１１，ＶＴ１２，ＶＴ２１，ＶＴ２２が変化した場合も温度変化による場合と同様の作用・効果があり、前述した（３）、または（４）、または（６）式に基づいてトルク検出電圧ＶＴ３１、またはＶＴ３２、またはＶＴ３を算出し、（７）、または（８）、または（９）、または（１０）式に基づいて故障検出電圧ＶＴＦ１、またはＶＴＦ２、またはＶＴＦ３を算出するので、磁場変化による影響を受けることなく、ピニオン軸５に作用するトルクを高精度で検出することができるとともに、磁歪式トルクセンサ３０の故障検出を高精度で行うことができ、磁歪式トルクセンサ３０が正常であるにも関わらず磁場変化に起因して故障と判断されるのを防止することができる。   Note that when the detection voltages VT11, VT12, VT21, and VT22 of the detection circuits 37 to 40 are affected by the change in the magnetic field, there are the same operations and effects as in the case of the change in temperature, and (3) or ( The torque detection voltage VT31, VT32, or VT3 is calculated based on the expression 4) or (6), and the failure detection voltage is calculated based on the expression (7), (8), or (9), or (10). Since VTF1, VTF2, or VTF3 is calculated, the torque acting on the pinion shaft 5 can be detected with high accuracy without being affected by the magnetic field change, and the failure detection of the magnetostrictive torque sensor 30 can be detected with high accuracy. It is possible to prevent the magnetostrictive torque sensor 30 from being judged as a failure due to a change in the magnetic field even though the magnetostrictive torque sensor 30 is normal. That.

この実施例では、故障検出電圧ＶＴＦ１を算出する際に、検出電圧ＶＴ１１，ＶＴ１２の差（差動）として求め、故障検出電圧ＶＴＦ２を検出電圧ＶＴ２１，ＶＴ２２の差（差動）として求め、さらに故障検出電圧ＶＴＦ３をこれら差動電圧ＶＴＦ１，ＶＴＦ２の和または差から求めたが、これらに代えて、検出電圧ＶＴ１１，ＶＴ１２の比（ＶＴ１１／ＶＴ１２）、および、検出電圧ＶＴ２１，ＶＴ２２の比（ＶＴ２１／ＶＴ２２）を求め、これら２つの比の積を故障検出出力とし、この故障検出出力に基づいて磁歪式トルクセンサ３０の故障検出を行うことも可能である。   In this embodiment, when calculating the failure detection voltage VTF1, the difference (differential) between the detection voltages VT11 and VT12 is obtained, the failure detection voltage VTF2 is obtained as the difference (differential) between the detection voltages VT21 and VT22, and the failure is further detected. The detection voltage VTF3 is obtained from the sum or difference of these differential voltages VTF1 and VTF2, but instead, the ratio of the detection voltages VT11 and VT12 (VT11 / VT12) and the ratio of the detection voltages VT21 and VT22 (VT21 / VT22) is obtained, and the product of these two ratios is used as a failure detection output, and failure detection of the magnetostrictive torque sensor 30 can be performed based on this failure detection output.

また、第１磁歪膜３１をピニオン軸５の軸線方向に２分割して、その一方を第１検出コイル３３に専用の磁歪膜、他方を第２検出コイル３４に専用の磁歪膜とし、第２磁歪膜３２をピニオン軸５の軸線方向に２分割して、その一方を第３検出コイル３５に専用の磁歪膜、他方を第２検出コイル３６に専用の磁歪膜として、４つの磁歪膜で構成することも可能である。   The first magnetostrictive film 31 is divided into two in the axial direction of the pinion shaft 5, one of which is a magnetostrictive film dedicated to the first detection coil 33 and the other is a magnetostrictive film dedicated to the second detection coil 34. The magnetostrictive film 32 is divided into two in the axial direction of the pinion shaft 5, one of which is a magnetostrictive film dedicated to the third detection coil 35 and the other is a magnetostrictive film dedicated to the second detection coil 36. It is also possible to do.

さらに、磁歪式トルクセンサ３０の故障検出出力の算出方法としては、前述した（３）式、（４）式で求めた差動電圧ＶＴ３１，ＶＴ３２に基づいて、次の（１１）式により、ＶＴ３１とＶＴ３２の差から故障検出電圧ＶＴＦ４を算出し、この故障検出電圧ＶＴＦ４が所定の閾値Ｂを超えたときに磁歪式トルクセンサ３０が故障であると判定することも可能である。
ＶＴＦ４＝ＶＴ３１−ＶＴ３２ ・・・ （１１）式
この故障検出電圧ＶＴＦ４に基づいて故障検出を行った場合も、温度変化や磁場変化による磁気特性の変化の影響を受けることなく、磁歪式トルクセンサ３０の故障検出を高精度で行うことができる。
なお、前述したように、差動電圧ＶＴ３１は、第１磁歪膜３１に対向配置された第１検出コイル３３と第２磁歪膜３２に対向配置された第３検出コイル３５の差動電圧であり、差動電圧ＶＴ３２は、第１磁歪膜３１に対向配置された第２検出コイル３４と第２磁歪膜３２に対向配置された第４検出コイル３６の差動電圧である。 Further, as a method of calculating the failure detection output of the magnetostrictive torque sensor 30, the following equation (11) is used to calculate VT31 based on the differential voltages VT31 and VT32 obtained by the above-described equations (3) and (4). It is also possible to calculate a failure detection voltage VTF4 from the difference between VT32 and VT32 and determine that the magnetostrictive torque sensor 30 is in failure when the failure detection voltage VTF4 exceeds a predetermined threshold B.
VTF4 = VT31−VT32 (11) Even when failure detection is performed based on this failure detection voltage VTF4, the magnetostrictive torque sensor 30 is not affected by changes in magnetic characteristics due to temperature changes or magnetic field changes. Can be detected with high accuracy.
As described above, the differential voltage VT31 is a differential voltage between the first detection coil 33 disposed opposite to the first magnetostrictive film 31 and the third detection coil 35 disposed opposite to the second magnetostrictive film 32. The differential voltage VT 32 is a differential voltage between the second detection coil 34 disposed opposite to the first magnetostrictive film 31 and the fourth detection coil 36 disposed opposite to the second magnetostrictive film 32.

〔他の実施例〕
この発明は、前述した実施例の電動パワーステアリング装置への適用に限るものではなく、ステアリング・バイ・ワイヤ・システムの車両用ステアリング装置にも適用可能である。ステアリング・バイ・ワイヤ・システムとは、操舵手段と転舵機構とが機械的に分離されていて、操舵手段に作用する操舵トルクに応じて、転舵機構に設けられたステアリングモータを駆動して車両の転舵輪を転舵させる操舵システムであり、この操舵手段に作用する操舵トルクの検出にこの発明に係る磁歪式トルクセンサを用いることができる。 [Other Examples]
The present invention is not limited to application to the electric power steering apparatus of the above-described embodiment, but can also be applied to a steering apparatus for a vehicle of a steering-by-wire system. In the steering-by-wire system, the steering means and the steering mechanism are mechanically separated, and the steering motor provided in the steering mechanism is driven according to the steering torque acting on the steering means. This is a steering system for turning steered wheels of a vehicle, and the magnetostrictive torque sensor according to the present invention can be used for detection of steering torque acting on the steering means.

この発明に係る磁歪式トルクセンサを備えた車両用電動パワーステアリング装置の概略構成図である。1 is a schematic configuration diagram of a vehicular electric power steering apparatus including a magnetostrictive torque sensor according to the present invention. 前記磁歪式トルクセンサの第１，第２検出コイルの出力特性図である。FIG. 3 is an output characteristic diagram of first and second detection coils of the magnetostrictive torque sensor. 前記磁歪式トルクセンサの第３，第４検出コイルの出力特性図である。It is an output characteristic figure of the 3rd and 4th detection coil of the magnetostriction type torque sensor. 前記磁歪式トルクセンサのトルク検出時の出力特性図である。It is an output characteristic view at the time of torque detection of the magnetostrictive torque sensor. 前記磁歪式トルクセンサの故障検出時の出力特性図である。It is an output characteristic view at the time of failure detection of the magnetostrictive torque sensor. 従来の磁歪式トルクセンサによるトルク検出と故障検出を説明する図である。It is a figure explaining the torque detection and failure detection by the conventional magnetostrictive torque sensor. 従来の磁歪式トルクセンサにおけるトルク検出時の出力特性図であり、温度変化による影響を説明するための図である。It is an output characteristic figure at the time of torque detection in the conventional magnetostriction type torque sensor, and is a figure for explaining the influence by temperature change. 従来の磁歪式トルクセンサにおける故障検出時の出力特性図であり、温度変化による影響を説明するための図である。It is an output characteristic figure at the time of failure detection in the conventional magnetostrictive torque sensor, and is a figure for explaining the influence by temperature change. 従来の磁歪式トルクセンサにおけるトルク検出時の出力特性図であり、磁場変化による影響を説明するための図である。It is an output characteristic figure at the time of torque detection in the conventional magnetostriction type torque sensor, and is a figure for explaining the influence by a magnetic field change. 従来の磁歪式トルクセンサにおいて磁場変化時の出力変化の一例を示す図である。It is a figure which shows an example of the output change at the time of the magnetic field change in the conventional magnetostrictive torque sensor. 従来の磁歪式トルクセンサにおいて故障検出時の出力特性図であり、磁場変化による影響を説明するための図である。It is an output characteristic figure at the time of failure detection in the conventional magnetostrictive torque sensor, and is a figure for explaining the influence by a magnetic field change.

符号の説明Explanation of symbols

５ ピニオン軸（シャフト）
１１ 電動機
３０ 磁歪式トルクセンサ
３１ 第１磁歪膜
３２ 第２磁歪膜
３３ 第１検出コイル
３４ 第２検出コイル
３５ 第３検出コイル
３６ 第４検出コイル
１００ 電動パワーステアリング装置（電動ステアリング装置） 5 Pinion shaft (shaft)
DESCRIPTION OF SYMBOLS 11 Electric motor 30 Magnetostrictive torque sensor 31 1st magnetostrictive film 32 2nd magnetostrictive film 33 1st detection coil 34 2nd detection coil 35 3rd detection coil 36 4th detection coil 100 Electric power steering apparatus (electric steering apparatus)

Claims (3)

シャフトに設けられた磁気異方性を互いに異にする第１磁歪膜と第２磁歪膜の磁気特性の変化に基づいて前記シャフトに入力されるトルクを検出する磁歪式トルクセンサであって、
前記第１磁歪膜に対向配置された第１検出コイルおよび第２検出コイルと、前記第２磁歪膜に対向配置された第３検出コイルおよび第４検出コイルと、を備え、
前記第１検出コイルの出力と前記第２検出コイルの出力との差に対応する第１信号と、
前記第３検出コイルの出力と前記第４検出コイルの出力との差に対応する第２信号と、
を求め、前記第１信号と前記第２信号の和または差に対応する故障検出信号に基づいて自身の故障を検出することを特徴とする磁歪式トルクセンサ。 A magnetostrictive torque sensor that detects torque input to the shaft based on a change in magnetic characteristics of the first and second magnetostrictive films having different magnetic anisotropies provided on the shaft,
A first detection coil and a second detection coil disposed opposite to the first magnetostrictive film, and a third detection coil and a fourth detection coil disposed opposite to the second magnetostrictive film,
A first signal corresponding to the difference between the output of the first detector output and the previous SL second detection coil of the coil,
A second signal corresponding to the difference between the output of the third detection output before Symbol fourth detection coil of the coil,
And detecting its own failure based on a failure detection signal corresponding to the sum or difference of the first signal and the second signal . シャフトに設けられた磁気異方性を互いに異にする第１磁歪膜と第２磁歪膜の磁気特性の変化に基づいて前記シャフトに入力されるトルクを検出する磁歪式トルクセンサであって、A magnetostrictive torque sensor that detects torque input to the shaft based on a change in magnetic characteristics of the first and second magnetostrictive films having different magnetic anisotropies provided on the shaft,
前記第１磁歪膜に対向配置された第１検出コイルおよび第２検出コイルと、前記第２磁歪膜に対向配置された第３検出コイルおよび第４検出コイルと、を備え、A first detection coil and a second detection coil disposed opposite to the first magnetostrictive film, and a third detection coil and a fourth detection coil disposed opposite to the second magnetostrictive film,
前記第１検出コイルの出力と前記第３検出コイルの出力との差に対応する第３信号と、A third signal corresponding to the difference between the output of the first detection coil and the output of the third detection coil;
前記第２検出コイルの出力と前記第４検出コイルの出力との差に対応する第４信号と、A fourth signal corresponding to the difference between the output of the second detection coil and the output of the fourth detection coil;
を求め、前記第３信号と前記第４信号の差に対応する故障検出信号に基づいて自身の故障を検出することを特徴とする磁歪式トルクセンサ。And detecting its own failure based on a failure detection signal corresponding to the difference between the third signal and the fourth signal. 操舵トルクを磁歪式トルクセンサによって検出し、検出した操舵トルクに応じて電動機を駆動して車両を転舵させる電動ステアリング装置において、In the electric steering device for detecting the steering torque by a magnetostrictive torque sensor and driving the electric motor according to the detected steering torque to steer the vehicle,
前記磁歪式トルクセンサは請求項１または請求項２に記載の磁歪式トルクセンサであることを特徴とする電動ステアリング装置。The electric steering apparatus according to claim 1, wherein the magnetostrictive torque sensor is the magnetostrictive torque sensor according to claim 1.
JP2004245124A 2004-08-25 2004-08-25 Magnetostrictive torque sensor and electric steering device Expired - Fee Related JP3964414B2 (en)

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JP2016176748A (en) * 2015-03-19 2016-10-06 本田技研工業株式会社 Magnetostrictive torque sensor and electrically driven power steering device

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